The proposed study will assess and characterize new genetic variants in LIPH and APOL1 that may relate to plasma lipoprotein lipid levels and their changes with exercise training. The study hypothesis is that genetic variants in LIPH and APOL1, candidate genes for HDL metabolism and composition, will partly explain the variability in plasma HDL levels and their changes with exercise training. The study will employ a standardized exercise training intervention in healthy 50-75 year olds, conduct baseline and final testing that includes NMR measurement of plasma lipoprotein lipids, sequence and screen newly identified candidate genes for HDL metabolism, genotype subjects at these newly identified gene loci, and assess the potential association of identified variants with plasma lipoprotein lipid levels and their responses to exercise training. The applicant will be prepared to perform mechanistic studies, including intermediate phenotype, mRNA expression, and blood protein level studies, to validate any associations found. The two months/yr she spends training with Dr. Eric Hoffman (Research Center for Genetic Medicine at Children's National Medical Center, Washington, DC) will train her to use emerging genetic and biochemical techniques to support her state-of-the-art genetics-exercise physiology research at the University of Maryland.